Color picture tube
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsYasufumi Wada, Toshihiro Daimon
Life of this patent
Estimating the term…
Abstract
A color picture tube in which an electron gun emits three electron beams arranged in line, in which the diameter of the spot (26) at the center of the screen in the in-line direction is smaller than that in the direction perpendicular to the in-line direction when the spot is in a just-focused state. Therefore the shape of the spot (27) at the periphery of the screen is generally a true circle. As a result, the resolution at the periphery of the phosphor screen is improved, and the more is suppressed.
Claims9
A color picture tube apparatus with three electron beams arranged in an in-line manner, emitted from an electron gun and being deflected by a self-convergence deflection magnetic field, the color picture tube apparatus comprising:
- a main lens portion in the electron gun, the main lens potion includes a main lens that has a focusing effect in the in-line direction and a direction perpendicular thereto and an electrostatic lens that is disposed at a stage immediately after the main lens and has a focusing effect in the in-line direction and a diverging effect in the direction perpendicular thereto;
- wherein
- when a spot formed in a central portion of a screen is just in focus, the spot in the central portion of the screen has a dimension along the in-line direction that is different from that along the direction perpendicular to the in-line direction, and
- the main lens portion further includes a four-pole lens that is disposed at a stage immediately before the main lens at a time of deflection in at least the central portion of the screen and has a diverging effect in the in-line direction and a focusing effect in the direction perpendicular thereto.
A color picture tube apparatus with three electron beams arranged in an in-line manner, emitted from an electron gun and being deflected by a self-convergence deflection magnetic field, the color picture tube apparatus comprising:
- a main lens portion in the electron gun, the main lens portion includes a main lens that has a focusing effect in the in-line direction and a direction perpendicular thereto, and an electrostatic lens that is disposed at a stage immediately after the main lens and has a focusing effect in the in-line direction and a diverging effect in the direction perpendicular thereto, and a four-pole lens that is disposed at a stage immediately before the main lens at a time of deflection in at least a central portion of a screen and has a diverging effect in the in-line direction and a focusing effect in the direction perpendicular thereto,
- wherein as a deflection angle becomes larger, the focusing effect and the diverging effect of the four-pole lens at the stage immediately before the main lens decrease.
A color picture tube apparatus with three electron beams arranged in an in-line manner, emitted from an electron gun and being deflected by a self-convergence deflection magnetic field, the color picture apparatus comprising:
- the electron gun having a first focusing electrode, second focusing electrode and an anode electrode;
- and
- a main lens that is formed by the second focusing elcetrode and the anode electrode and has a focusing effect in the in-line direction and a direction perpendicular thereto;
- and
- a four-pole lens that is formed by the first focusing electrode and the second focusing electrode and has a diverging effect in the in-line direction and a focusing effect in the direction perpendicular thereto at a time of deflection in a central portion of a screen;
- and
- a pair of flat plates that are provided in the anode electrode and are each arranged on a virtual plane parallel with a horizontal axis and a tube axis so as to extend toward the focusing electrode.
Dependencies are inferred from the claim text.